A tree harvester of this kind is known, for instance, from Swedish Patent Specification 8600948-7 publication number 463 067). The limbing head and the felling head of this earlier known tree harvester can be connected detachably to one another and the assembly is mounted as a unit for pivotal movement about a pivot point at one end of an arm system to a tree-felling position in which the limbing head and the felling head are able to commonly grip the tree to be felled. The arm system includes at least one fixed first boom and a second boom which can be moved longitudinally in relation to the fixed boom, e.g. telescoped, wherein the limbing head is attached to the further boom and the felling head is attached to the fixed, first boom. The limbing head and the felling head are mutually separated when the second boom is extended out from the first boom, and the tree is limbed by moving the limbing head away from the felling head with the trunk of the tree held firmly by the gripping claws of the felling head. The axially movable second boom is moved in the longitudinal direction of the first boom with the aid of pivot arms.
One drawback with the aforesaid known arrangement is that very long booms and pivot arms are required in order to obtain an acceptable length of movement between the limbing head and the felling head in conjunction with a tree limbing and cross-cutting operation.